Article unstacking system

Abstract

An article unstacking system includes an infeed conveyor which delivers stacks of articles to an unstacker which has an inclined support wall and a carriage reciprocatively movable parallel to the support wall and carrying a platform disposed in a plane perpendicular to the support wall for cooperation therewith to define a generally V-shaped trough into which the stack is received. The carriage is moved upwardly until the top article is engaged by a discharge roller which lifts it from and peels it off the stack. To facilitate separation of the top article, the stack is retracted a short distance as soon as the top article is engaged by the discharge rollers, so that the carriage undergoes repeated up and down movements until the stack is depleted. Carriage drive is effected by short-stroke and long-stroke air cylinders, with the former being carried by the movable element of the latter.

I claim: 
     
       1. Apparatus for removing articles one at a time from the top of a stack of articles having an axis intersecting the top and bottom articles in the stack at the centers thereof, said apparatus comprising: stack support means for receiving the stack thereon, said support means including carriage means movable with respect to the remainder of said support means for effecting reciprocating movement of the stack in directions parallel to its axis; drive means coupled to said carriage means for effecting movement thereof and of the stack thereon between a discharge condition wherein the top article in the stack is disposed in a discharge position and a withdrawn condition below said discharge condition; discharge means engageable with the top article in the stack when it is disposed in its discharge position for removing it from the stack and moving it from its discharge position; and control means coupled to said drive means for controlling the operating thereof, of, said control means being responsive to movement of the top article to its discharge position for causing movement of the carriage means to its withdrawn condition while said discharge means is moving the top article from its discharge position to facilitate separation of the top article from the stack, said control means being responsive to removal of the top article from its discharge position and from the stack when said carriage means is in its withdrawn condition for causing movement of the carriage means back to its discharge condition. 
     
     
       2. The apparatus of claim 1, wherein said stack support means includes an inclined support wall, said carriage means being movable parallel to said support wall for sliding the stack therealong. 
     
     
       3. The apparatus of claim 2, wherein said discharge means includes a discharge roller disposed at the upper end of said support wall for rotation about an axis parallel to said support wall, said roller being dimensioned for frictional engagement with an edge of the top article lying along said support wall for lifting that edge from the stack and feeding the article off the stack. 
     
     
       4. The apparatus of claim 3, and further comprising retaining means engageable with the top article in the stack in its discharge position for preventing movement of the article away from the support wall in response to engagement of the article by said discharge roller. 
     
     
       5. The apparatus of claim 2, wherein said carriage means includes support wheels disposed for rolling engagement with said support wall to provide support for said carriage means during the reciprocating movement thereof. 
     
     
       6. The apparatus of claim 1, wherein said carriage means includes a platform engageable with the bottom of the stack and guide means for guiding the reciprocating movement of said carriage means. 
     
     
       7. The apparatus of claim 1, and further comprising rack means disposed on said remainder of said support means and pinion means mounted on said carriage means and disposed for meshing engagement with said rack means to guide the reciprocating movement of said carriage means. 
     
     
       8. Apparatus for removing articles one at a time from the top of a stack of articles having an axis intersecting the top and bottom articles in the stack at the centers thereof, said apparatus comprising: stack support means for receiving the stack thereon, said support means including carriage means movable with respect to the remainder of said support means for effecting reciprocating movement of the stack in directions parallel to its axis; drive means coupled to said carriage means for effecting movement thereof and of the stack thereon between a discharge condition wherein the top article in the stack is disposed in a discharge position and a withdrawn condition below said discharge condition; said drive means including first motor means movable over only a short distance in extending and retracting directions between fully extended and retracted conditions for moving said carriage means toward and away from its discharge condition, and second motor means movable over a long distance in extending and retracting directions for moving said carriage means toward and away from its discharge condition; discharge means engageable with the top article in the stack when it is disposed in its discharge position for removing it is disposed in its discharge position for removing it from the stack; and control means coupled to said first and second motor means for controlling the operation thereof, said control means being responsive to disposition of said first motor means in its fully retracted condition when the top article in the stack is not disposed in its discharge position for moving said first motor means to its fully extended condition, said control means being responsive to disposition of said first motor means in its fully extended condition when the top article of the stack is not in its discharge position for moving said second motor means in an extending direction until the top article in the stack is in its discharge position, said control means being responsive to arrival of the top article in the stack at its discharge position for moving said first motor means to its retracted condition to facilitate separation of the top article from the stack. 
     
     
       9. The apparatus of claim 8, wherein each of said first and second motor means includes a fixed means and a movable means, said fixed means of said second drive means being coupled to the remainder of said support means, said fixed means of said first motor means being carried by said movable means of said second motor means, said movable means of said first motor means being coupled to said carriage means. 
     
     
       10. The apparatus of claim 8, wherein each of said first and second motor means includes a pneumatic cylinder. 
     
     
       11. The apparatus of claim 10, wherein the stroke of said first drive means is substantially equal to the depth of an article in directions parallel to said axis. 
     
     
       12. The apparatus of claim 8, wherein said second motor means is movable between fully extended and fully retracted conditions, said control means being responsive to disposition of said second motor means in its fully extended condition when there is no article in a discharge position for moving said second motor means to is fully retracted condition. 
     
     
       13. A system for removing articles one at a time from stacks of articles each having an axis intersecting the top and bottom articles in the stack at the centers thereof, said system comprising: infeed conveyor means for delivering stacks of articles sequentially to an unstacking station; stack support means at said unstacking station for receiving a stack from said infeed conveyor means, said support means including carriage means reciprocatively movable with respect to the remainder of said support means to and from a fully-retracted stack-receiving configuration for effecting reciprocating movement of a supported stack in directions parallel to its axis; drive means coupled to said carriage means for effecting movement thereof and of the stack thereon between a discharge condition wherein the top article in the stack is disposed in a discharge position and a withdrawn condition below said discharge condition; discharge means engageable with the top article in the stack when it is disposed in its discharge position for removing it from the stack and moving it from its discharge position; and control means coupled to said drive means and to said infeed conveyor means for controlling the operation thereof, said control means being responsive to disposition of said carriage means in its fully-retracted stack-receiving configuration for operating said infeed conveyor means to deliver a stack to said stack support means, said control means being responsive to delivery of a stack to said stack support means for stopping said infeed conveyor means, said control means being responsive to movement of the top article to its discharge position for causing movement of the carriage means to its withdrawn condition while said discharge means is moving the top article from its discharge position to facilitate separation of the top article from the stack, said control means being responsive to removal of the top article from its discharge position and from the stack when said carriage means is in its withdrawn condition for causing movement of the carriage means back to its discharge condition. 
     
     
       14. The system of claim 13, and further comprising a drive assembly coupled to said discharge means and to said infeed conveyor means for operating same. 
     
     
       15. The system of claim 14, wherein said drive assembly includes continuously operating motive means, and clutch means coupling said motive means to said infeed conveyor means, said control means engaging said clutch means when said carriage means is disposed in its stack-receiving configuration and disengaging said clutch means after a stack has been delivered from said infeed conveyor to said stack support means. 
     
     
       16. The system of claim 14, wherein said discharge means includes a discharge roller frictionally engageable with the top article in the stack for lifting it and feeding it from the stack. 
     
     
       17. The system of claim 13, wherein said stack support means includes an inclined support wall. 
     
     
       18. The system of claim 17, wherein said discharge means includes a discharge roller disposed at the upper end of said support wall for rotation about an axis parallel to said support wall. 
     
     
       19. The system of claim 18, and further comprising guide means including rack means disposed on said remainder of said support means and pinion means mounted on said carriage means and disposed for meshing engagement with said rack means to guide the reciprocating movement of said carriage means.